1. Field of the Invention
This invention relates to a magnetic recording medium, more particularly, to a magnetic tape that has a reduced frictional coefficient, improved running durability and which is free from edge damages without lowering S/N characteristics.
2. Development of the Invention
Magnetic recording tapes for audio, video or computer applications have a magnetic recording layer with a smooth finish to provide improved sensitivity, particularly higher output in the high-frequency range. Magnetic recording tapes having such a smooth finish cannot be uniformly and orderly wound or rewound, so that tension variations during such winding or rewinding reduce its running properties and cause unstable output. In addition, the tape may be easily distorted or damaged.
To eliminate these defects, magnetic recording tapes having a backing layer on the surface of the support thereof opposite the magnetic recording layer have been proposed. However, even such tapes are not without flaws as conventional binders for use in the backing layer, such as vinyl chloride-vinyl acetate-maleic acid copolymers, have low wear resistance and tenacity which reduces tape running durability, and which results in an increased frictional coefficient and waving or creases at the tape edges.
As is generally known, when a magnetic recording medium (especially a magnetic tape) which has a backing layer to provide improved running properties and high running durability is rolled or stacked in sheets, projections and recesses in the backing layer transfer to the surface of the adjacent magnetic layer, thereby damaging the surface characteristics of the magnetic layer to such an extent that the electromagnetic characteristics--especially S/N characteristics--of the magnetic recording medium are impaired.
Further when too great an emphasis is placed on achieving good running properties, the backing layer obtained has so rough a surface that when the magnetic medium is rolled or stacked for storage, the projections and recesses in the backing layer will be transferred to the surface of the magnetic recording layer, and greatly impair the S/N characteristics of the medium.